It is widely believed that the US supreme court has decided that George W Bush should be the next president. A closer look at the densely packed ruling - six opinions expressed in 65 pages - reveals that the court decided nothing of the sort.

The ruling expresses no preference for Mr Bush, or for Vice-President Al Gore. It merely makes it virtually impossible for Mr Gore to win. There is a theoretical possibility that the Democrats will send in their legal cavalry for one last charge.

For the supreme court has, in effect, tossed the final decision on a vote recount back to the supreme court of Florida in Tallahassee. That court ordered a statewide manual recount of all so-called undervotes - ballot papers on which mechanical counting devices could not detect a presidential choice.

The state court ruling was Al Gore's last hope of overtaking Mr Bush's slender lead in Florida and snatching from him the state's 25 electoral college votes. But when Mr Bush appealed to the supreme court in Washington, the justices there ordered the recount to be halted. Last night's 5-4 ruling confirms the court's judgment that the recount breached the constitutional requirement for all votes to be treated equally.

However, the supreme court has dangled a tantalising last hope before the Gore lawyers: if the Florida court can come up with a standard procedure for the recount then it may in theory resume the process.

But the phrase "in theory" is crucial. The supreme court issued its convoluted ruling at 10pm last night, local time - only two hours before the deadline for Florida to name its 25 electoral college voters.

Hours before the ruling, the Florida House of Representatives, dominated by Republicans, endorsed an electoral college slate which is bound to vote for Mr Bush in the college poll on December 18. The Democrats could, in desperation, dispute the validity of the deadline and try to field an alternative slate of electoral college voters, based on a recount, but that would risk a full-scale constitutional crisis.

For many Americans, the legal drama has thrown up uncomfortable questions about the bedrock of their constitution, based on the clear separation of powers of the three pillars of government: executive, legislative, and judicial.

Also at issue is the fundamental relationship between federal and state government. As a broad principle, the US supreme court defers to the state courts where issues of state law are involved. In its latest ruling, however, the Washington jurists have overruled their Tallahassee counterparts, raising intriguing and perhaps disturbing questions about the essence of US governance.

Never before has the supreme court intervened in the electoral system to decide who shall have the highest office in the land. Usually, of course, it is the president who chooses the nine justices, not the other way round. Of the current justices, seven were nominated by Republican presidents, and only two by President Clinton. That raises the queasy doubt that the system has moved from patronage to blatant partisanship.

One of the four dissenting judges, Justice John Paul Stevens, has included in his written opinion a lament for the system itself. The court's action, he wrote, "can only lend credence to the most cynical appraisal of the work of judges throughout the land."

He went on: "It is confidence in the men and women who administer the judicial system that is the true backbone of the rule of law. Time will one day heal the wound to that confidence that will be inflicted by today's decision.

"One thing, however, is certain: although we may never know with complete certainty the identity of the winner of this year's presidential election, the identity of the loser is perfectly clear. It is the nation's confidence in the judge as an impartial guardian of the rule of law."